Left factorials: Difference between revisions

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 !10000 has 35656 digits
 </pre>
+Faster Implementation
+<lang csharp>
+using System;
+using System.Numerics;
+namespace LeftFactorial
+{
+    class Program
+    {
+        static void Main(string[] args)
+        {
+            for (int i = 0; i <= 10; i++)
+            {
+                Console.WriteLine(string.Format("!{0} : {1}", i, LeftFactorial(i)));
+            }
+            for (int j = 20; j <= 110; j += 10)
+            {
+                Console.WriteLine(string.Format("!{0} : {1}", j, LeftFactorial(j)));
+            }
+            for (int k = 1000; k <= 10000; k += 1000)
+            {
+                Console.WriteLine(string.Format("!{0} : has {1} digits", k, LeftFactorial(k).ToString().Length));
+            }
+            Console.ReadKey();
+        }
+        private static BigInteger LeftFactorial(int n)
+        {
+            BigInteger result = 0;
+            BigInteger subResult = 1;
+            for (int i = 0; i < n; i++)
+            {
+                if (i == 0)
+                {
+                    subResult = 1;
+                }
+                else
+                {
+                    subResult *= i;
+                }
+                result += subResult;
+            }
+            return result;
+        }
+    }
+}
+</lang>
 =={{header|D}}==